const Papa=require("papaparse");
const errors=require("./errors.js");
import { RemoteSource } from "./RemoteSource";

import { ParseErrors, ParseResults, Parsers, RemoteSources,  RemoteSourceSettings } from "./interfaces";
import { PublicPapaParseOptions, PrivatePapaParseOptions } from "./interfacesPapaParse";

export class ParserForCSV implements Parsers
{
    private _datasRemoteSource: RemoteSources;
    private _datas2Parse:string="";
    private _parseResults:ParseResults|undefined=undefined;
    public options: PublicPapaParseOptions=
    {
        delimiter: "",
        newline: "",
        quoteChar: '"',
        escapeChar: '"',
        transformHeader: function(field: string, index: number): string { return field.trim() },
        preview: 0,
        comments: "",
        fastMode: undefined,
        transform: undefined
    }
    private _privateOptions: PrivatePapaParseOptions=
    {
        header: true,
        download: false,
        downloadRequestHeaders: undefined, 
        skipEmptyLines: "greedy",
        withCredentials: undefined
    }
    
    // L'instance d'une autre classe que RemoteSource peut être passée au constructeur
    constructor(datasRemoteSource?: RemoteSources)
    {
        if(datasRemoteSource !== undefined)
            this._datasRemoteSource=datasRemoteSource;
        else
            this._datasRemoteSource=new RemoteSource({ url:"" });
    }

    public setRemoteSource(source: RemoteSourceSettings)
    {
        this._datasRemoteSource=new RemoteSource(source);
    }

    get datasRemoteSource() : RemoteSources
    {
        return this._datasRemoteSource;
    }

    set datas2Parse(datas: string)
    {
        if(datas.trim().length === 0)
            throw new Error(errors.parserNeedDatas);
        else
            this._datas2Parse=datas.trim();
    }

    get datas2Parse() : string
    {
        return this._datas2Parse;
    }

    get parseResults() : ParseResults|undefined
    {
        return this._parseResults;
    }

    get privateOptions() : any
    {
        return this._privateOptions;
    }

    public async parse():  Promise<any>
    {
        const parser=this;
        let parseContent=""; 
        if(parser._datasRemoteSource.url !== "")
        {
            parseContent=parser._datasRemoteSource.url;
            this._privateOptions.download=true;
            this._privateOptions.withCredentials=parser._datasRemoteSource.withCredentials;
            if(parser._datasRemoteSource.headers !== undefined)
            {
                this._privateOptions.downloadRequestHeaders={};
                for(let header of parser._datasRemoteSource.headers)
                    this._privateOptions.downloadRequestHeaders[header.key]=header.value;
             }
        }
        else if(parser._datas2Parse !== "")
            parseContent=parser._datas2Parse;
        else
            throw new Error(errors.parserNeedSource);
            
        return new Promise((resolve,reject) =>
        {
            Papa.parse(parseContent,
            {
                delimiter: this.options.delimiter,
                newline: this.options.newline,
                quoteChar: this.options.quoteChar,
                escapeChar: this.options.escapeChar,
                header: true,
                transformHeader: this.options.transformHeader,
                preview: this.options.preview,
                comments: this.options.comments,
                complete: function(results :any)
                {
                    // Attention, Papa Parse peut accepter un nom de champ vide ou en doublon
                    // De plus dans le cas de doublons, il renomme les champs surnémaires "_n" au nom du champs
                    // Or, ceci peut être le vrai nom d'un champ
                    // A voir, si cette regression disparait dans l'avenir. Test unitaire désactivé en attendant
                    let realFields: string[]=[], parseErrors: ParseErrors[]=[];
                    for(let field of results.meta.fields)
                    {
                        let checkField=field.trim();
                        if(checkField !== "" && realFields.indexOf(checkField) === -1) 
                           realFields.push(checkField);
                        else
                            parseErrors.push({ row:-1, message: errors.parserFieldNameFail});
                    }
                    if(realFields.length === 0)
                        reject(new Error(errors.parserFieldsNotFound));
                    else
                    {
                        parser._parseResults=
                        {
                            datas: results.data,
                            errors: parseErrors.concat(results.errors), // result.errors = errreurs rencontrées par Papa Parse
                            fields: realFields,
                        };
                        resolve(true);
                    }
                },
                download: this._privateOptions.download,
                downloadRequestHeaders: this._privateOptions.downloadRequestHeaders, 
                skipEmptyLines:"greedy",
                fastMode: this.options.fastMode,
                withCredentials: this._privateOptions.withCredentials, 
                transform: this.options.transform
            });
        });
   }
}